Dr. Irvin joined the Hoddle laboratory in 2001 as a post doctoral scholar. Dr Irvin has had a heavy focus on researching the glassy-winged sharpshooter, Homalodisca vitripennis (Germar), and its Mymarid wasp biological control agentsGonatocerus ashmeadi, G. fasciatus, G. triguttatus, and G. tuberculifemur.

Dr. Irvin was promoted to Assistant Specialist in 2007, and awarded a Western Region Sustainable Agriculture Research and Education (Western SARE) grant to investigate the use of nectar cover crops for sustainable pest control in California vineyards. This four-year project ended in 2010.

Currently, Dr. Irvin is investigating the potential of insect honeydew and several drought tolerant flowering plants that are native to California for enhancing the survival and reproduction of Tamarixia radiata, a parasitoid that attacks Asian citrus psyllid (ACP).

Degrees

Professional Affiliations

Member of NZIAS (New Zealand Institute for Agricultural Science) since 1996.

Member of New Zealand Plant Protection Society since 1997.

Member of New Zealand Ecological Society since 1999.

Member of New Zealand Royal Society since 1999.

Member of Entomological Society of America since 2001.

Research Interests

Dr. Irvin is a graduate of Lincoln University, New Zealand, where she completed a Bachelor of Horticultural Science and was awarded first-class honors. Her honors project compared hover fly (Diptera: Syrphidae) numbers, gut fullness, female egg load and pollen preference of three New Zealand hover fly species between arable and florally-diverse habitats. Dr. Irvin showed for the first time the high dependency of New Zealand predatory hover flies on floral resources (Irvin, 1996; Irvin et al., 1999a).

Dr. Irvin went on to complete her PhD in Entomology and her thesis examined the use of understorey management for the enhancement of leafroller (Lepidoptera: Tortricidae) parasitoids (Dolichogenidea tasmanica) in apple orchards located in Canterbury, New Zealand. The results of her work (Irvin, 1999; Irvin et al., 1999b; Irvin et al., 2000; Irvin et al., 2006a) showed that sowing buckwheat, coriander, or alyssum in apple understoreys can enhance field populations of D. tasmanica and increase leafroller parasitism in the field.

In April 2001, Dr. Irvin joined the Hoddle laboratory at University of California, Riverside, and has been involved in researching the biology of three Gonatocerus parasitoids associated with the biological control of the glassy-winged sharpshooter (Homalodisca vitripennis), a significant pest of many agriculturally important crops in southern California. From 2001-2007 her research determined which lemon cultivar maximized H. vitripennis oviposition for use in future experiments (Irvin & Hoddle, 2004), egg age utilization by three Gonatocerus spp. (Irvin & Hoddle, 2005a), the biological potential and competitive ability of three Gonatocerus parasitoids in the laboratory (Irvin & Hoddle, 2005b; Irvin et al., 2006b), the influence of parasitoid intraspecific competition on the sex ratio of subsequent progeny (Irvin & Hoddle, 2006), and the effect of several food resources on Gonatocerus spp. longevity (Irvin & Hoddle 2007; Irvin et al., 2007) .

During this time, Dr. Irvin also conducted research investigating the fitness costs for transgenic mosquitoes expressing the green fluorescent protein marker. The results of her work (Irvin et al., 2004) showed that survival, fecundity, and longevity are significantly reduced in transgenic mosquitoes relative to the untransformed laboratory strain. This research was the first of its kind in the world and has important implications for the development and utilization of this technology for mosquito control programs, or suppression of disease transmission, which are based on genetic modification.

Dr. Irvin built on her previous Gonatocerus work by investigating protein- and dye-marking of G. ashmeadi for mark-capture studies (Irvin et al. 2012) and measuring egg maturation, oosorption, and wing wear in G. ashmeadi (Irvin and Hoddle, 2009). During the latter research, she discovered that G. ashmeadi is a synovigenic parasitoid, a finding that contradicts current reproductive classification. Quarantine studies were also performed to determine the viability and potential of two “new association” Gonatocerus parasitoids to be introduced into California as biological control agents of H. vitripennis (Irvin et al. 2009, Irvin and Hoddle 2010, Irvin and Hoddle 2011). Additionally, Dr. Irvin conducted research to measure real lifetime contributions of individual female G. ashmeadi to parasitism of H. vitripennis egg masses under field conditions, and determine the ecological significance of brochosome deposition on H. vitripennis egg masses and its effect on parasitism rates in the field (Irvin et al. 2014).

In 2007, Dr. Irvin received a four year grant from Western Region Sustainable Agriculture Research and Education (Western SARE) to investigate the use of nectar cover crops for sustainable pest control in California vineyards. Results were published in three manuscripts (Irvin et al. 2014, Irvin and Hoddle 2015, Irvin et al. 2016). This work demonstrated that an irrigated buckwheat cover crop unexpectedly resulted in higher densities of pestiferous leafhoppers on grape leaves which could be attributed to these pests preferring well-irrigated, vigorously growing vines. An irrigated buckwheat cover crop was also associated with increased berry size, reduced sugar content of berries, and reduced berry quality because of increased insect feeding damage. Dispersal of natural enemies from buckwheat cover crop plots was also investigated and these results are currently being prepared for publication.

Currently, Dr. Irvin is investigating the potential of several drought tolerant flowering plants that are native to California as cover crops for enhancing the survival and reproduction of Tamarixia radiata. This Eulophid parasitoid attacks the nymphs of Asian citrus psyllid (ACP). ACP feeds on the stems and leaves for citrus trees and transmits a bacterial disease called Huanglongbing (HBL or citrus greening) which kills citrus trees. Potential food resources commonly found in citrus orchards, such as citrus flower nectar, brown soft scale honeydew and honeydew from ACP, are also being investigated as food resources for T. radiata.

29. Irvin, N. A., Hoddle, M. S. 2008. Should Neoclassical Biological Control Agents from Argentina Be Released in California for Control of the Glassy-winged Sharpshooter? Pierce's Disease Research Symposium, San Diego, USA, December 15-17, pp. 66-69.

28. Irvin, N. A., Hoddle, M. S. 2007. Should Neoclassical Biological Control Agents from Argentina Be Released in California for Control of the Glassy-winged Sharpshooter? Pierce's Disease Research Symposium, San Diego, USA, December 12-14, pp. 90-93.